Process element with structural element

Abstract

The invention relates to a treatment element (1), such as a welding head (3) or an anvil, for treating a material, the treatment element (1) having a substantially cylindrical or cylindrical segment-shaped carrier surface (2) which is intended to come into contact with the material during the treatment, the treatment element (1) being arranged to rotate about its longitudinal axis (10) during the treatment, so that the carrier surface (2) moves in the circumferential direction and rolls over the material to be treated, wherein at least one structural element (4) is arranged on the carrier surface (2), the structural element (4) protruding away from the carrier surface (2) in the radial direction, wherein the structural element (4) has a top surface which is intended to come into contact with the material to be treated. In order to provide a treatment element (1) which enables reliable welding at high feed rates, it is proposed according to the invention that the top surface has a base section and at least one recess section, the distance between the recess section and the longitudinal axis (10) being smaller than the base section, wherein the base section and the recess section are arranged next to one another in a sectional view perpendicular to the longitudinal axis (10).

Description

[0001] This invention relates to a processing element for ultrasonically treating materials, such as a sonotrode or anvil. For example, a corresponding processing element is described in EP 3 209 433 B1.

[0002] Ultrasonic waves are increasingly being used to bond nonwoven materials. Two nonwoven fabric segments to be bonded are placed one above the other in the gap between a welding head and an anvil, and the welding head is subjected to ultrasonic vibrations. Due to the friction caused by the ultrasonic vibrations, localized heating occurs on the contact surfaces, melting the thermoplastic components, especially in nonwoven materials. The molten components of the material segments to be bonded flow into each other, ensuring a strong bond upon cooling.

[0003] In this way, it is possible to join the corresponding sections of nonwoven fabric together to form side seams when manufacturing diapers.

[0004] When processing nonwoven fabrics, material collection is often necessary. For this purpose, additional elastic threads are inserted between the nonwoven fabric segments to be joined. The segments are then connected to each other on at least two bonding surfaces, and the threads are secured between these surfaces during processing using ultrasonic waves. This creates a positive connection between the threads and the nonwoven fabric segments in two spatial directions, which are perpendicular to each other. In this way, material collection can be achieved.

[0005] In this configuration, the processing element may have a substantially cylindrical or cylindrical segment-shaped carrier surface designed to contact the material during processing. Then, during processing, the processing element rotates about its longitudinal axis, causing the carrier surface to roll over the material to be processed.

[0006] In this configuration, the carrier surface typically has at least one structural element that protrudes radially from the carrier surface, such that the structural element has a top surface designed to contact the material to be processed. Then, actual welding is performed in the area between the top surface of the structural element and the sealing surface of a counter-element arranged at a certain distance therefrom.

[0007] In the case of online anchoring, the elongated structural element typically extends along the longitudinal axis of the processing element, such that the structural element is usually at an angle to the orientation of the thread, typically a right angle. Therefore, the structural element connects the thread segmentally to the nonwoven fabric segment. Areas where the thread can move freely alternate with segments to which the thread is connected to the nonwoven fabric segment. This connection can be achieved in the spatial direction by force-fitting or by material fit between the nonwoven fabric and the thread, without form-fitting in this spatial direction. If the thread is stretched during ultrasonic processing, the thread segment is fixed, which results in the nonwoven fabric being collected when the thread is relaxed after processing.

[0008] For example, the reverse element can be a soldering head, and the processing element can be an anvil. The invention is explained below based on this embodiment, which is a preferred embodiment. However, in principle, the processing element can be designed as a soldering head, and the reverse element as an anvil.

[0009] During the process, the surface of the carrier with the structural elements rolls on the material to be processed, thereby causing the structural elements to be welded in particular.

[0010] Processing speed is limited by existing technology and equipment.

[0011] In principle, the feed rate can be increased, which is the speed at which material passes through the gap between the processing element and the counter element.

[0012] However, a welding head that acts on the material at a fixed frequency will no longer apply enough energy to achieve a reliable weld. This is because at higher feed rates, the material is in contact with the sealing surface of the welding head for a shorter time, resulting in less "stroke" applied to the material by the welding head.

[0013] This can be partially compensated for by increasing the force of the welding head pressing against the material being processed. As a result, more energy is transferred to the material per stroke of the welding head. However, this leads to more friction and the formation of molten parts at the interface between the material layers to be welded, which is formed by ultrasonic treatment. That is, in the so-called joint zone, structural elements are pressed out of the joint zone, which also leads to a poorer joint because there are no longer enough thermoplastic parts available in the joint zone. Alternatively, or in combination, the amplitude of the ultrasonic vibration can be increased. This will also transfer more energy to the material per stroke of the welding head. However, this can only be achieved within a limited range. If the welding head is operated with excessively high vibration amplitude, the welding head material may be damaged.

[0014] To achieve higher processing speeds, so-called "welding wheels" have been used, in which several welding heads are arranged on a wheel to increase the contact time during the wheel's rotation. However, this solution is very complex.

[0015] Additionally, attaching the yarn to the nonwoven fabric presents an extra problem: overly narrow structural elements can lead to insufficient yarn clamping because the clamping force is reduced due to the small interaction surface with the nonwoven fabric segment, corresponding to the top surface of the structural element. On the other hand, if the structural element is chosen to be too wide, the interaction surface and therefore the clamping force increase, but this also leads to increased friction with the material being processed. Furthermore, if the structural element is too wide, the free space for unimpeded yarn movement is reduced, negatively impacting the material's wrinkle-reducing properties.

[0016] Based on the aforementioned prior art, the problem of the present invention is to specify a processing element for reliable soldering.

[0017] According to the present invention, the problem is solved by having a top surface having a base segment and at least one recessed segment, the recessed segment being less than the distance from the longitudinal axis to the base segment, wherein, in a cross-sectional view perpendicular to the longitudinal axis, the base segment and the recessed segment are arranged adjacent to each other, and wherein the recess formed by the recessed segment does not extend to the surface of the support member.

[0018] As the structural element rolls on the material, it can receive the plasticized part in the recessed section, thereby reducing the amount of plasticized part pressed out from the joint area.

[0019] In the case of online anchoring, the concentration of melt in the concave section further improves wire clamping.

[0020] The recessed section also reduces the effective interaction surface, thus reducing friction with the material. Simultaneously, structural elements can be made wider, allowing for better wire fixation. Furthermore, the recessed section means that less force must be applied between the processing and counter-processing elements to achieve the same processing effect. Additionally, an improved feel has been observed in the resulting product.

[0021] In a preferred embodiment, the recess preferably has a depth of less than 1 mm, and most preferably between 0.05 mm and 0.2 mm.

[0022] In a further preferred embodiment, the recessed portion is formed as a groove, which is preferably aligned not only in the circumferential direction. If the groove is aligned in the circumferential direction, the groove preferably does not completely bypass the surface of the support member, but extends only at a circumferential angle of <360°, preferably at a circumferential angle of less than 45° and most preferably less than 25°. It is also possible that several grooves are spaced apart in the circumferential direction.

[0023] The groove is not intended to interrupt the welding process, but rather to receive the molten material so that it remains essentially in place and can be used to join material layers.

[0024] As has been shown, by increasing the pressure of the welding head on the material to be processed, the groove can prevent harmful displacement of the melt at the location of the groove. The melt then moves only upward into the groove. Thus, the groove acts as a container for the material being melted.

[0025] In a preferred embodiment, the width of the groove is less than 1 mm, and preferably less than 0.6 mm. More preferably, the width of the groove is between 0.2 and 0.4 mm.

[0026] Depending on the material to be welded, if the cross-sectional area of ​​the groove is less than 0.15mm...2 That might be sufficient. Preferably, the cross-sectional area is even less than 0.05 mm. 2 And ideally, the cross-sectional area is 0.015 mm. 2 and 0.04mm 2 between.

[0027] In a preferred embodiment, the structural element has a plurality of grooves, preferably at least three, not aligned circumferentially on its top surface, and these grooves are preferably arranged parallel to each other. The grooves successfully hold the molten material in their respective positions, thus a plurality of grooves is advantageous.

[0028] In a further preferred embodiment, the top surface of the structural element has a main segment and at least one chamfered segment adjacent to the main segment in the circumferential direction. The main segment is substantially flat or forms a convex bend with a radius of curvature corresponding to the distance between the main segment and the cylindrical axis. Either the chamfered segment is angled relative to the main segment such that the angle between the main segment and the chamfered segment is less than 180°, or the chamfered segment is convexly bendable, wherein if the main segment is convexly bendable, the radius of curvature of the chamfered segment is smaller than the radius of curvature of the main segment. Preferably, at least one recessed segment is arranged in the main segment. The chamfered segment is used to gradually prepare material for welding contact between the main segment and the reverse element. At the transition between the main segment and the chamfered segment, the slope or curvature of the top surface changes. This ensures that the distance between the structural element and the reverse element continuously decreases during the use of the processing element until the minimum distance between the structural element and the reverse element has been achieved.

[0029] In a further preferred embodiment, the top surface is provided with two chamfered segments adjacent to the main segment in the circumferential direction, which are angled relative to the main segment such that the main segment and the chamfered segments each enclose an angle of less than 180°. Therefore, during processing, the top surface of the structural element not only has entry chamfered segments but also exit chamfered segments, thus, even at the end of the processing of the structural element, the force exerted by the reverse element on the processing element only gradually decreases.

[0030] In a further preferred embodiment, the top surface of the structural element is an elongated shape having a length l and a width b, where l > b. Preferably, this length does not extend parallel to the longitudinal axis, but is preferably substantially perpendicular to the longitudinal axis.

[0031] In a further embodiment, the structural element and the recessed section arranged on the top surface extend continuously along the entire length l of the processing element, the orientation of the length l being substantially parallel to the longitudinal axis. Preferably, the length l of the structural element is significantly greater than the width b of the structural element, the width b being arranged substantially perpendicular to the length l.

[0032] In a further embodiment, the structural element also extends substantially along the longitudinal axis of the processing element, wherein the structural element and the recessed section disposed on the top surface extend in a serpentine shape. It will be understood that, in this case, the base section is also serpentine.

[0033] The present invention also relates to an ultrasonic welding apparatus having a processing element as described above. In addition to the processing element, the ultrasonic welding apparatus also has a counter element having a sealing surface, which can be arranged with the processing element such that a gap is formed between the top surface of a structural element of the processing element and the sealing surface of the counter element, in which the material to be processed can be arranged, wherein, in a cross-sectional view perpendicular to the longitudinal axis of the processing element, the sealing surface has at least segmented concave-bending welding sections.

[0034] As mentioned above, the reverse element can be the welding head, and the processing element can be the anvil. The curved sections of the welding segment increase the contact time between the welding head and the anvil, allowing more energy to be introduced into the material. This also increases the feed rate without having to increase the force of the welding head pressing on the material to be processed.

[0035] In another preferred embodiment, the radius of curvature of the concave bend of the reverse element is specified to be approximately equal to the radius of curvature of the main section of the processing element. In practice, it is particularly preferred that the radius of curvature of the concave bend of the reverse element is slightly larger than the radius of curvature of the main section of the processing element. In this case, the difference between the two radii of curvature corresponds to the gap width maintained between the sealing surface and the top surface of the structural element during the welding process.

[0036] In a further embodiment, the counter element has a groove for at least partially receiving at least one wire, the groove being oriented in a feed direction in which material to be processed moves through a gap between the processing element and the counter element. The material to be processed comprises at least two material web segments and at least one wire located between the two material web segments. In this way, the processing element according to the invention can also be used in an ultrasonic processing apparatus to produce collectable material.

[0037] In another preferred embodiment, the sealing surface has an entry section located near the welding section and is either non-curved or concave with a radius of curvature greater than that of the welding section. Here, also, at the transition between the entry section and the welding section, the slope or curvature of the sealing surface changes such that, within the section of the entry section, the distance between the processing element and the counter element gradually decreases until a minimum distance corresponding to the distance between the welding section and the top surface of the structural element is reached. This entry section is arranged such that material moving through the gap in the feed direction first contacts the entry section and then contacts the welding section.

[0038] It is advantageous if the dimensions of the entry section and the welding section are approximately the same.

[0039] Other advantages, features and possible applications of the present invention will become apparent from the following description of preferred embodiments and drawings.

[0040] Figure 1 A three-dimensional view of an ultrasonic welding device is shown.

[0041] Figure 2 It shows Figure 1 A detailed enlarged view of the section marked with an X.

[0042] Figure 3 It shows Figure 2 Detailed enlarged image;

[0043] Figure 4 It shows Figure 1 Side view of an ultrasonic welding device.

[0044] Figure 5 It shows Figure 4 A magnified partial view.

[0045] Figure 6 A schematic diagram of a further embodiment of the processing element according to the present invention is shown, and

[0046] Figure 7 It shows Figure 6 An enlarged view of the diagram in the image.

[0047] Figure 1 A perspective view of an ultrasonic welding apparatus is shown. The ultrasonic welding apparatus has a processing element 1 in the form of an anvil, which is designed here as a roller rotatable about a longitudinal axis 10. At least one transverse seam bar 11 with a bearing surface 2 is arranged on the roller. Counter elements 3 in the form of welding heads are arranged opposite each other.

[0048] Here, ultrasonic vibration can be used to excite the counter element 3. The material to be processed then moves between the carrier surface 2 and the sealing surface of the welding head 3 facing the carrier surface 2, so that the material's movement speed corresponds to the peripheral speed of the processing element 1. The gap between the carrier surface 2 and the welding head 3 must be selected such that ultrasonic vibration is transmitted to the material during processing, and the thermoplastic part melts at the joint surface.

[0049] Figure 2 It shows Figure 1 A detailed enlarged image.

[0050] As can be seen, multiple structural elements 4 are arranged on the surface 2 of the support member. The structural elements 4 have an elongated shape and are oriented in the circumferential direction. The structural elements 4 come into contact with the material during processing and determine the welding type of the material introduced during processing. For example, ultrasonic welding equipment can be used to produce the side seams of diapers made of non-woven fabric materials.

[0051] Figure 3 It shows Figure 2 A detailed enlarged view shows structural element 4 clearly visible. Two structural elements 4 are arranged adjacent to each other in the circumferential direction (relative to the longitudinal axis 10). In the axial direction, many such pairs of structural elements are arranged adjacent to each other.

[0052] Each structural element has a main segment 6 and two chamfered segments 7 and 8, which are more curved than the main segment 6. A groove 5 has been introduced into the main segment 6, which extends perpendicular to the circumferential direction in the illustrated embodiment. The grooves do not necessarily have to be perpendicular to the circumferential direction. However, for the effects of the invention to be achieved, they should not be arranged parallel to the circumferential direction. If the grooves are arranged parallel to the circumferential direction, they should not extend over the entire structural element 4.

[0053] During welding, structural element 4 rolls on the material to be processed, causing the chamfered section 8 to come into contact with the material first. Due to the angled arrangement of the chamfered section 8, the distance between the opposing sealing surfaces of structural element 4 and counter element 3 gradually decreases in this region until it reaches a minimum distance in the region of main section 6. Main section 6 may be convexly curved, such that the radius of curvature substantially corresponds to the distance between the top surface of structural element 4 and the longitudinal axis 10 of processing element 1.

[0054] A groove 5 with a depth of 0.1 mm and a width of 0.3 mm is introduced into the main section 6. Molten material can penetrate into the resulting groove, so that it is essentially held in place and will not be squeezed out of the joint area by the structural elements.

[0055] Figure 4 It shows Figure 1 A side view of the ultrasonic welding equipment. The sealing surface, i.e., the surface facing the carrier or structural element 4, is surface 9.

[0056] Figure 5 It shows Figure 4A magnified partial view. Surface 9 here consists of an entry section 9a and a welding section 9b. The welding section 9b is concave and curved, with a radius of curvature substantially the same as that of the main section of the processing element. This ensures that the material remains in contact with the welding head for a longer period during processing, allowing more energy to be introduced into the material to be processed. In this embodiment, the entry section 9a is not curved, thus ensuring that the material to be processed is initially guided into the narrow gap in the region of the entry section 9a. The gap is minimal in the region of the welding section 9b and remains substantially constant in the welding section region. In this case, welding is primarily performed by the welding section 9b, but the entry section 9a can already contribute to the welding at its end facing the welding section 9b.

[0057] at last, Figure 6 and Figure 7 An alternative embodiment of the processing element 1 according to the invention is shown, which is particularly suitable for producing collectable materials. For this purpose, at least one line is guided between two web segments of the material to be processed, the at least one line being connected to the web segments in the segments by a structural element 4 in a force-fit or material-fit manner. The structural element 4 extends continuously over the entire extent of the anvil 1 in the direction of the longitudinal axis 10. Furthermore, the structural element 4, and therefore the groove 5, also extends in a serpentine shape (see...). Figure 7 ).because Figure 6 and Figure 7 The design shown features a line that is stably connected to the web section of the material, while reducing friction between the processing element 1 and the material.

[0058] List of reference numerals

[0059] 1. Processing element (anvil)

[0060] 2. Surface of the bearing component

[0061] 3. Reverse components (welding heads)

[0062] 4 structural components

[0063] 5 grooves

[0064] 6 main sections

[0065] 7,8 chamfered sections

[0066] 9. Sealing surface

[0067] 9a Entering Section

[0068] 9b Welding section

[0069] 10. Longitudinal axis

[0070] 11. Seam edge

Claims

1. A processing element (1) for processing material, the processing element having a cylindrical or cylindrical segment-shaped carrier surface (2) intended to contact the material during processing, the processing element (1) intended to rotate about a longitudinal axis of the processing element (1) during processing such that the carrier surface (2) moves in a circumferential direction and rolls on the material to be processed, at least one structural element (4) arranged on the carrier surface (2), the structural element (4) projecting radially above the carrier surface (2), the structural element (4) having a top surface intended to contact the material to be processed, characterized in that, The top surface has a base segment and at least one recessed segment, the distance between the recessed segment and the longitudinal axis (10) being less than that of the base segment, wherein, in a cross-sectional view perpendicular to the longitudinal axis (10), the base segment and the recessed segment are arranged adjacent to each other, wherein the recess formed by the recessed segment does not extend to the surface (2) of the support member.

2. The processing element (1) according to claim 1, characterized in that, The depth of the recess is less than 1 mm.

3. The processing element (1) according to claim 1, characterized in that, The recessed section is formed as a groove (5), and the groove (5) is not aligned in the circumferential direction.

4. The processing element (1) according to claim 3, characterized in that, The width of the groove (5) is less than 1 mm.

5. The processing element (1) according to claim 3, characterized in that, The cross-sectional area of ​​the groove (5) is less than 0.15 mm².

6. The processing element (1) according to claim 3, characterized in that, The structural element (4) has a plurality of non-circularly aligned grooves (5) on the top surface, each groove (5) being arranged parallel to each other.

7. The processing element (1) according to claim 1, characterized in that, The top surface includes a main section (6) and at least one chamfered section (7, 8), the main section (6) being formed as a flat or convex bend with a radius of curvature corresponding to the distance between the main section (6) and the cylindrical axis, the chamfered section (7, 8) being adjacent to the main section (6) in the circumferential direction, the chamfered section also being angled relative to the main section (6) such that the main section (6) and the chamfered section (7, 8) form an angle of <180° and / or are convex bends, wherein if the main section (6) is convex bends, the radius of curvature of the chamfered section (7, 8) is smaller than the radius of curvature of the main section (6), wherein the at least one recessed section is arranged in the main section (6).

8. The processing element (1) according to claim 1, characterized in that, At least two of the structural elements (4) are spaced apart from each other in the circumferential direction.

9. The processing element (1) according to claim 1, characterized in that, The processing element (1) is designed as an anvil.

10. The processing element (1) according to claim 1, characterized in that, The top surface is an elongated shape with a length l and a width b, where l > b.

11. The processing element (1) according to claim 1, characterized in that, The structural element (4) arranged on the top surface and the recessed section extend continuously along the overall length l of the processing element (1), wherein the length l is oriented parallel to the longitudinal axis (10).

12. An ultrasonic welding apparatus comprising a processing element (1) according to any one of the preceding claims and a counter element (3), the counter element (3) having a sealing surface (9) arranged opposite to the processing element (1) such that a gap is formed between the top surface and the sealing surface, in which material to be processed can be arranged, wherein, In a cross-sectional view perpendicular to the longitudinal axis (10) of the processing element (1), the sealing surface (9) has at least segmented concave-bent welded sections (9b).

13. The ultrasonic welding equipment according to claim 12, characterized in that, The radius of curvature of the concave curved section of the anti-element (3) is equal to the radius of curvature of the main section (6) of the processing element (1).

14. The ultrasonic welding equipment according to claim 12, characterized in that, The counter element (3) has a groove for at least partially receiving at least one wire, the groove being oriented in the feed direction in which the material to be processed moves through the gap between the processing element (1) and the counter element (3), wherein the material to be processed comprises at least two material web segments and the at least one wire, wherein the at least one wire is positioned between the two material web segments.

15. The ultrasonic welding equipment according to claim 12, characterized in that, The sealing surface (9) has an entry section (9a) located near the welding section (9b) and is either non-curved or concave with a radius of curvature greater than that of the welding section (9b).

16. The ultrasonic welding equipment according to claim 14, characterized in that, The processing element (1) is designed to rotate in the feeding direction, through which the material to be processed passes between the processing element (1) and the counter element (3), wherein the entry section (9a) and the welding section (9b) are arranged such that the material moving through the gap in the feeding direction first contacts the entry section (9a) and then contacts the welding section (9b).

17. The ultrasonic welding equipment according to claim 15, characterized in that, The entry section (9a) and the welding section (9b) are equal in size.

18. The ultrasonic welding equipment according to claim 12, characterized in that, The reverse element (3) is designed as a welding head.

Images